Sequential acquisition of Potato virus Y strains by Myzus persicae favors the transmission of the emerging recombinant strains

Authors: MONDAL, SHAONPIUS - Cornell University; Gray, Stewart

Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2017
Publication Date: 7/14/2017
Citation: Mondal, S., Gray, S.M. 2017. Sequential acquisition of Potato virus Y strains by Myzus persicae favors the transmission of the emerging recombinant strains. Virus Research. 241:116-124. https://doi.org/10.1016/j.virusres.2017.06.023.
DOI: https://doi.org/10.1016/j.virusres.2017.06.023

Interpretive Summary: Emerging strains of Potato virus Y are more damaging to the U.S. potato industry because they can cause a tuber necrotic disease which reduces the quality of the potato and renders it unmarketable. The rapid emergence and expansive distribution of the new strains is unprecedented and the factors driving the changes are unknown. This research investigated whether aphids visiting multiple plants infected with different strains of PVY will ultimately transmit the new strains of the virus more efficiently than the old strain. Transmission of the new strains was significantly greater than the old strain regardless of the order in which aphids acquired both viruses. If the aphids acquired two of the new virus strains then each of the new strains were transmitted with equal efficiency. Many potato fields have plants infected with different strains of the virus and most aphids will visit multiple plants in the field. The ability of the new strains to outcompete the old strain during the transmission process likely contributes to the increase in the new strains that has been observed in recent years.

Technical Abstract: In the past decade recombinant strains of potato virus Y (PVY) have overtaken the ordinary strain, PVYO, as the predominant viruses affecting the US seed potato crop. Aphids may be a contributing factor in the emergence of the recombinant strains, but studies indicate that differences in transmission efficiency of individual PVY strains either from single or mixed infections, although variable, are not generally significant. Multiple strains of PVY are present in all potato production areas and common in many potato fields. Therefore, it is likely that individual alate aphids moving through a potato field will sequentially encounter multiple strains as they “taste test” multiple potato plants while looking for a suitable host. This study examined the transmission likelihood and efficiency of three common PVY strains when acquired sequentially by individual aphids. Green peach aphids (Myzus persicae, Sulzer) were allowed a 2-3 min acquisition access period (AAP) on potato leaves infected with PVYO, PVYN:O or PVYNTN, followed by another 2-3 min AAP on a second potato leaf infected with a different PVY strain before being transferred to healthy potato seedlings for a 24 hour inoculation access period. All possible combinations of the three strains were tested. Strain-specific infection of the recipient plants was determined by TAS-ELISA and RT-PCR 3-4 week post-inoculation. The recombinant strains, PVYN:O and PVYNTN, were transmitted more efficiently than PVYO when they were sequentially acquired regardless of the order acquired. PVYN:O and PVYNTN were transmitted with similar efficiencies when they were sequentially acquired regardless of the order. The recombinant strains appear to preferentially bind to the aphid stylet over PVYO or they may be preferentially released during inoculation. This may contribute to the increased incidence of the recombinant strains over PVYO in fields or production regions where multiple PVY strains are detected.